1. Field of the Invention
This invention relates to a pilot valve suitable for use with a nebulizer which has high pressure gas delivered directly to the unit waiting for utilization.
2. Description of the Previously Published Art
A problem with previous nebulizer operation has recently been recognized as very important to the proper administrations of fluid drugs and medicaments by the aerosol or nebulized mode of administration. Previously, nebulization of medication to obtain the desired particle sizes and density has been continuously delivered to the patient throughout both the inhalation and exhalation phases of a breathing cycle. This led to merely approximating the dosage actually delivered during the critical period of inhalation. Variations in the length of the phases of the breathing cycle would defeat proper dosage based on these approximations. Likewise, intermittent nebulization which is patient controlled or by a metered dose inhaler requires a degree of coordination not necessarily present in a patient requiring the treatment either by condition of age or the severity of illness. Further, where intermittent nebulization is provided by sensing the negative pressure of patient inhalation and using that sensing to trigger or initiate high pressure gas flow, the gas, i.e., air or oxygen, which is stored under pressure is normally maintained at some distance for the nebulizer unit. When the system detects that the patient is inhaling, the valve at the gas source is opened and there is some delay before the gas reaches the nebulizer unit. This delay is due to several factors including the length of the delivery tube, the inside diameter of the tubing, the pressure being used and the compressibility of the gas.
These factors result in a delay in delivery which is a patient compliance problem because the system may be delivering medication for an indeterminate interval of the inhalation cycle.
Without knowing when in the inhalation cycle the delivery has begun, there is no way of knowing how much medicament has been utilized. This is exacerbated by the fact that the high pressure gas when finally reaching the nebulizer is not at the steady pressure state needed by the system in order to provide the proper particle size and density. The optimum size and density should be inhaled at the critical time, i.e., as near as possible to the start of inhalation. Only by achieving this can the proper concentration of medicament and, therefore, the proper dosages be prescribed with the confidence that the patient will receive the prescribed dosage in the form and amount necessary for complete effective utilization by the patient without waste and possibly contamination of the local environment where the nebulizer is exhausting into the surrounding air as during continuous nebulization.
3. Objects of the Invention
It is, therefore, an object of this invention to provide a valve designated herein as a pilot immediately adjacent the nebulizer gas inlet which has the high pressure gas supplied directly to the pilot valve so that when the valve is opened in response to system determinations, the gas at high pressure can be substantially immediately delivered at a steady state of flow and pressure to the nebulizer unit to nearly or substantially instantaneously begin nebulization producing the proper distribution range and of particle sizes at the desired density.
These and further objects of the invention will become apparent as the description of the invention proceeds.